Resonating element, resonator, electronic device, electronic apparatus, and mobile object

ABSTRACT

A piezoelectric resonating element includes a piezoelectric substrate that includes a rectangular vibrating section and a thick section integrally formed with the vibrating section, excitation electrodes, and lead electrodes. The thick section includes a first thick section and a second thick section of which one end is formed continuous to the first thick section. The first thick section includes a first inclined section of which the thickness changes and a first thick section main body of a quadrangle column shape, and at least one slit is provided in the first thick section.

BACKGROUND

1. Technical Field

The present invention relates to a resonator having a thickness shearvibration mode as the main vibration, and particularly to a vibratingelement having a so-called inverted mesa structure, a resonator, and anelectronic device, an electronic apparatus, and a mobile object usingsuch a resonator.

2. Related Art

An AT cut quartz crystal resonator is a resonator in which the mainvibration mode which is excited is a thickness shear vibration, andsince it is appropriate for miniaturization and increases in frequency,and presents a cubic curve with an excellent frequency-temperaturecharacteristic, it has a wide variety of applications in piezoelectricoscillators and electronic apparatuses.

JP-A-2004-165743 (patent literature 1) discloses an AT cut quartzcrystal resonator of a so-called inverted mesa structure that includes arecess on a portion of the main plane and is designed to achieve highfrequency. The length of the Z′-axis direction of a quartz crystalsubstrate is set to be longer than the length of the X-axis direction,and a so-called Z′-long substrate is used.

JP-A-2009-164824 (patent literature 2) discloses an AT cut quartzcrystal resonator of an inverted mesa structure in which thick supportsections (thick sections) are continuously formed respectively on threesides of a thin rectangular vibrating section and one side of the thinvibrating section is configured to be exposed. Furthermore, a quartzcrystal resonator element is an in-plane rotation AT cut quartz crystalsubstrate in which the X-axis and the Z′-axis of the AT cut quartzcrystal substrate is rotated in the range of −120° to +60° around theY′-axis respectively, and has a structure (multi-cavity structure)excellent in securing a vibration area and mass-production.

JP-A-2006-203700 (patent literature 3) and JP-A-2002-198772 (patentliterature 4) disclose an AT cut quartz crystal resonator of an invertedmesa structure in which thick support sections are continuously formedrespectively on three sides of a thin rectangular vibrating section andone side of the thin vibrating section is configured to be exposed, andin a quartz crystal resonator element, the length of a quartz crystalsubstrate in the X-axis direction is longer than the length thereof inthe Z′-axis direction, and a so-called X-long substrate is used.

JP-A-2002-033640 (patent literature 5) discloses an AT cut quartzcrystal resonator of an inverted mesa structure in which thick supportsections are continuously formed respectively on two adjacent sides anda thick section having an L-shape in a plan view is provided in a thinrectangular vibrating section, and two sides of the thin vibratingsection are configured to be exposed. In a quartz crystal substrate, aZ′-long substrate is used.

However, in JP-A-2002-033640 (patent literature 5), in order to obtainthe L-shaped thick section, the thick section is cut out along a line αand a line β as described in FIGS. 1C and 1D of JP-A-2002-033640, butsince cutting is performed on the premise of cutting using a mechanicalprocess such as dicing, or the like, there are problems in that damagesuch as chipping, cracking, or the like is inflicted on a cut surface,and an ultra-thin section is broken. In addition, other problems occursuch as the generation of unwanted vibration that may cause spuriousvibrations in a vibration area, an increase of a CI value, or the like.

JP-A-2001-144578 (patent literature 6) discloses an AT cut quartzcrystal resonator of an inverted mesa structure in which a thick supportsection is continuously formed on one side only of a thin vibratingsection and three sides of the thin vibrating section are configured tobe exposed.

JP-A-2003-264446 (patent literature 7) discloses an AT cut resonator ofan inverted mesa structure that is designed to achieve high frequency byforming a recess so as to oppose both main planes that are front andrear surfaces of a quartz crystal substrate. For the quartz crystalsubstrate, an X-long substrate is used, and a configuration is proposedin which excitation electrodes are provided in regions where flatness ofa vibration area formed in the recess is secured.

With regard to a thickness shear vibration mode in which excitation isshown in a vibration area of an AT cut quartz crystal resonator, it isknown that the vibration displacement distribution has an ellipsoidalshape having a long diameter in the X-axis direction due to anisotropyof an elastic constant. JP-A-2-079508 (patent literature 8) discloses apiezoelectric resonator in which a thickness shear vibration is excitedwith a pair of ring-shaped electrodes arranged on both the front andrear surfaces of a piezoelectric substrate so as to be symmetric interms of front and rear sides. The difference between an outercircumferential diameter and an inner circumferential diameter of thering-shaped electrodes is set so that the ring-shaped electrodes areexcited only in a symmetric zero-order mode and seldom excited in otherinharmonic higher-order modes.

JP-A-9-246903 (patent literature 9) discloses a piezoelectric resonatorin which the shapes of a piezoelectric substrate and excitationelectrodes provided on the front and rear surfaces of the piezoelectricsubstrate is set to be ellipsoidal shapes.

JP-A-2007-158486 (patent literature 10) discloses a quartz crystalresonator in which the shapes of both ends of a quartz crystal substratein the long side direction (X-axis direction) and both ends ofelectrodes in the X-axis direction are set to be semi-elliptical shapes,and the ratio of the major axis to the minor axis (major axis/minoraxis) of the ellipse is set to 1.26.

JP-A-2007-214941 (patent literature 11) discloses a quartz crystalresonator in which elliptical excitation electrodes are formed on anelliptical quartz crystal substrate. The ratio of the major axis to theminor axis is desirably 1.26:1, but when unevenness in manufacturingdimensions, or the like is considered, a ratio in the range of about1.14 to 1.39:1 is effective.

JP-UM-A-61-187116 (patent literature 12) discloses a piezoelectricresonator that is configured to include a cutout or a slit between avibrating section and a support section so as to further improve theenergy trapping effect of a thickness shear piezoelectric resonator.

When miniaturization of a piezoelectric resonator is designed toachieve, there is a case where deterioration in electric characteristicsor degradation of a frequency aging characteristic are caused due toresidual stress caused by an adhesive. JP-A-9-326667 (patent literature13) discloses a quartz crystal resonator in which a cutout or a slit isprovided between a vibrating section and a support section of a flatrectangular AT cut quartz crystal resonator. It is said that the use ofsuch a configuration can hinder residual stress from expanding to avibration area.

JP-A-2009-158999 (patent literature 14) discloses a resonator in which acutout or a slit is provided between a vibrating section and a supportsection of an inverted mesa type piezoelectric resonator in order toease (alleviate) mounting strain (stress).

JP-A-2004-260695(patent literature 15) discloses a piezoelectricresonator in which conduction of electrodes on the front and rearsurfaces is secured by providing a slit (through hole) in a supportsection of an inverted mesa type piezoelectric resonator.

JP-A-2009-188483 (patent literature 16) discloses a quartz crystalresonator that suppresses a higher-order contour unwanted mode byproviding a slit in a support section of a thickness shear vibrationmode AT cut quartz crystal resonator.

In addition, JP-A-2003-087087 (patent literature 17) discloses aresonator that suppresses spurious vibrations by providing a slit in acontinuous section of a thin vibrating section and a thick holdingsection, in other words, in a residual section having an inclinedsurface, of an inverted mesa type AT cut quartz crystal resonator.

In recent years, demand for miniaturization, high frequency, and highperformance of a piezoelectric device has intensified. However, whenminiaturization and high frequency are intended, it is clear that thereis a problem in that, with regard to a piezoelectric resonator of theabove-described configuration, a CI value of the main vibration, a ratioof CI values of proximate spurious vibrations (=CIs/CIm, wherein CIm isa CI value of the main vibration, and CIs is a CI value of spuriousvibrations, and a standard example is 1.8 or higher) and the like do notsatisfy the demands. Particularly, when a frequency is a high frequencyof several hundred MHz, the thickness of an electrode film of anexcitation electrode formed in a piezoelectric vibration element and alead electrode are problematic. When only the main vibration of thepiezoelectric vibration element is intended to be in a trapping mode,there are problems in that the electrode film is thin, ohmic lossarises, and the CI value of the piezoelectric vibrating elementincreases.

In addition, when the thickness of the electrode film is thickened inorder to prevent ohmic loss of the film, there is a problem in that manyinharmonic modes other than the main vibration are shifted to trappingmodes, and thus, the ratio of CI values of proximate spurious vibrationsis not attained.

SUMMARY

An advantage of some aspects of the invention is to provide apiezoelectric vibrating element, a piezoelectric resonator, and anelectronic device that achieve high frequency (100 to 500 MHz), reducethe CI value of the main vibration, and satisfy electronic demand suchas the ratio of the CI value of spurious vibrations, and an electronicapparatus using such a piezoelectric resonator according to the aspectof the invention.

Application Example 1

This application example is directed to a piezoelectric vibratingelement having: a substrate that includes a vibrating section includinga vibration area and a thick section that is formed integrally with thevibrating section and is thicker than the vibrating section; and anexcitation electrode that is provided in the vibration area, in whichthe thick section includes a first thick section that is provided alongone side of the vibrating section, and a second thick section that isprovided along another side connected to the above side, the first thicksection and the second thick section are continuous with each other atrespective end thereof, a main plane of the first thick sectionprotrudes further than one main plane of the vibrating section, theother main plane of the first thick section and the other main plane ofthe vibrating section are the same plane, one main plane of the secondthick section protrudes further than one main plane of the vibratingsection, the other main plane of the second thick section and the othermain plane of the vibrating section are the same plane, the first thicksection includes a first inclined section of which the thicknessincreases as the first thick section is apart from one circumferentialedge thereof that comes into continuous contact with a first outer edgeof the vibrating section toward the other circumferential edge, and afirst thick section main body that comes into continuous contact withthe other circumferential edge of the first inclined section, and atleast one slit is provided in the first thick section.

According to the configuration, a high-frequency piezoelectric vibratingelement using a fundamental wave is miniaturized and easilymass-produced. Furthermore, since expansion of stress resulting fromadhesion and fixation can be suppressed by providing a slit in the firstthick section, there is an effect of obtaining a piezoelectric vibratingelement having an excellent frequency-temperature characteristic,CI-temperature characteristic, and frequency aging characteristic. Inaddition, since excitation electrodes, lead electrodes, and padelectrodes respectively use metal materials of different compositions,and are configured to have proper film thicknesses, there is an effectof obtaining a piezoelectric vibrating element having a small CI valueof the main vibration and a high ratio of a CI value of proximatespurious vibrations to the CI value of the main vibration, that is, ahigh CI value ratio.

Application Example 2

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein, centeringaround an X axis of an orthogonal coordinate system including the X axisas an electrical axis, a Y axis as a mechanical axis, and a Z axis as anoptical axis that are crystal axes of quartz crystal, the substrate setsan axis obtained by inclining the Z axis toward the −Y direction of theY axis to a Z′ axis, sets an axis obtained by inclining the Y axistoward the +Z direction of the Z axis to a Y′ axis, has a planeincluding the X axis and the Z′ axis as the main plane, and is a quartzcrystal substrate having thickness in the direction along the Y′ axis.

By configuring a piezoelectric vibrating element using such apiezoelectric substrate cut out at a cutting angle, there is an effectof obtaining a high-frequency piezoelectric vibrating element withrequired specifications that is configured at a more proper cuttingangle having a frequency-temperature characteristic conforming to thespecifications, a low CI value, and a high CI value ratio.

Application Example 3

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein the firstthick section and the second thick section protrude in the +Y directionof the Y′ axis.

By including a first and a second thick sections in this manner, thereare advantages of avoiding strain to be imposed on a vibrating sectionand fixing a piezoelectric vibrating element to a package.

Application Example 4

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein the secondthick section is provided in the +Z′ direction of the Z′ axis.

By including a second thick section in this manner, the strength of avibrating section can be maintained even after two-step inclinationgenerated by etching in the −Z′ direction of the Z′ axis is removed, andtherefore, there is an advantage that a piezoelectric vibrating elementcan be fixed to a package.

Application Example 5

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein the firstthick section is provided in the +X direction of the X axis.

By including a first thick section in this manner, inclination generatedby etching in the +X direction of the X axis becomes long, andtherefore, there are advantages of avoiding strain imposed on avibrating section and fixing a piezoelectric vibrating element to apackage.

Application Example 6

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein the slit isprovided in the first thick section main body along the boundary sectionof the first inclined section and the first thick section main body.

According to the configuration, since a piezoelectric vibrating elementis miniaturized and a slit is provided along the boundary section of thefirst inclined section and the first thick section main body, theexpansion of stress arising during adhesion and fixation of thepiezoelectric vibrating element can be suppressed. Accordingly, there isan effect of obtaining a piezoelectric vibrating element havingexcellent frequency-temperature characteristic, CI (CrystalImpedance)-temperature characteristic, and frequency agingcharacteristic.

Application Example 7

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein the slit isprovided within the first inclined section as being separated from oneside of the vibrating section.

According to the configuration, since a piezoelectric vibrating elementis miniaturized and a slit is provided within the first inclined sectionas being separated from one side of the vibrating section, the slit canbe easily formed and the expansion of stress arising during adhesion andfixation of the piezoelectric vibrating element can be suppressed.Accordingly, there is an effect of obtaining a piezoelectric vibratingelement having excellent frequency-temperature characteristic, andCI-temperature characteristic.

Application Example 8

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein the slitincludes a first slit disposed in the first thick section main body, anda second slit that is provided within the first inclined section asbeing separated from one side of the vibrating section.

According to the configuration, since a piezoelectric vibrating elementis miniaturized and two slits are provided in the first thick section,the expansion of stress arising during adhesion and fixation of thepiezoelectric vibrating element can be suppressed. Accordingly, there isan effect of obtaining a piezoelectric vibrating element havingexcellent frequency reproducibility, frequency-temperaturecharacteristic, CI-temperature characteristic, and frequency agingcharacteristic.

Application Example 9

This application example is directed to the piezoelectric vibratingelement according to the above application example, wherein the firstslit is provided in the first thick section main body along the boundarysection of the first inclined section and the first thick section mainbody.

In this manner, since the first slit is provided along the boundarysection of the first inclined section and the first thick section mainbody, there is an effect of further suppressing the expansion of stressarising during adhesion and fixation of the piezoelectric vibratingelement.

Application Example 10

This application example is directed to a piezoelectric resonatorincluding: the piezoelectric vibrating element according to the aboveapplication example; and a package in which the piezoelectric vibratingelement is accommodated.

According to the configuration, as a high-frequency piezoelectricvibrating element is miniaturized and stress resulting from adhesion andfixation of the piezoelectric vibrating element can be reduced, there isan effect of obtaining a piezoelectric resonator having excellentfrequency reproducibility, frequency-temperature characteristic,CI-temperature characteristic, and frequency aging characteristic.Furthermore, since excitation electrodes, lead electrodes, and padelectrodes respectively use metal materials of different compositions,and are configured to have proper film thicknesses, there is an effectof obtaining a piezoelectric resonator having a small CI value of themain vibration and a high ratio of a CI value of proximate spuriousvibrations to the CI value of the main vibration, that is, a high CIvalue ratio, and a piezoelectric resonator having a small capacitanceratio.

Application Example 11

This application example is directed to an electronic device including:the piezoelectric vibrating element according to Application Example 1;an electronic component; and a package in which the piezoelectricvibrating element and the electronic component are accommodated.

In this manner, if an electronic device in which a package accommodatesa piezoelectric vibrating element and an electronic component isconfigured, when a thermistor is applied to the electronic component,for example, the thermistor of a temperature-sensing element is disposedvery close to the piezoelectric vibrating element, and therefore, thereis an effect of swiftly sensing a temperature change of thepiezoelectric vibrating element. In addition, by building the electroniccomponent therein, there is an effect of reducing load on an apparatusby adding a temperature control function to the apparatus to be used.

Application Example 12

This application example is directed to the electronic device accordingto the above application example, wherein the electronic component isany one of a variable capacitance element, a thermistor, an inductor,and a capacitor.

In this manner, if an electronic device (piezoelectric device) isconfigured by using any one of a variable capacitance element, athermistor, an inductor, and a capacitor in the electronic component,there is an effect of realizing an electronic device more suitable for adevice with required specifications in a small size at low cost.

Application Example 13

This application example is directed to an electronic device accordingto the above application example including: a package in which theoscillator circuit for driving the piezoelectric vibrating element areaccommodated.

According to the configuration, there is an effect of obtaining ahigh-frequency (for example, 490 MHz band) electronic device(piezoelectric device) in a small size having excellent frequencyreproducibility, frequency-temperature characteristic, and frequencyaging characteristic. In addition, since such a piezoelectric deviceuses a piezoelectric vibrating element of a fundamental mode, acapacitance ratio is low and a frequency variable width is wide.Furthermore, there is an effect of obtaining an electronic device(piezoelectric device) having a satisfactory S/N ratio.

In addition, there are effect of configuring a piezoelectric oscillator,a temperature-compensated piezoelectric oscillator, and the like as apiezoelectric device, and an electronic device (piezoelectric device)having excellent frequency reproducibility, frequency agingcharacteristic, and frequency-temperature characteristic.

Application Example 14

This application example is directed to an electronic apparatusincluding: the piezoelectric resonator according to Application Example10.

According to the configuration, since the piezoelectric resonator of theabove application example is used in an electronic apparatus, there isan effect of configuring an electronic apparatus having excellentfrequency stability at a high frequency and including a referencefrequency source with a satisfactory S/N ratio.

Application Example 15

This application example is directed to a mobile object including: thepiezoelectric resonator according to Application Example 10.

According to the configuration, since the piezoelectric resonator of theabove application example is used in a mobile object, there is an effectof configuring a mobile object having excellent frequency stability at ahigh frequency and including a reference frequency source with asatisfactory S/N ratio.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIGS. 1A to 1F are schematic diagrams showing a configuration of apiezoelectric vibrating element according to a first embodiment of theinvention. FIG. 1A is a plan view, FIG. 1B is a cross-sectional view ofline P-P, FIG. 1C is a cross-sectional view of line Q-Q, FIGS. 1D, 1E,and 1F are cross-sectional view of line Q-Q showing modificationexamples of a slit shape.

FIG. 2 is a diagram describing the relationship between an AT cut quartzcrystal substrate and crystal axes.

FIG. 3A is a plan view showing configurations of a lead electrode and apad electrode, and FIG. 3B is a plan view showing a configuration of anexcitation electrode.

FIG. 4 is a plan view showing a configuration of a modification exampleof the piezoelectric vibrating element.

FIG. 5 is a plan view showing a configuration of another modificationexample of the piezoelectric vibrating element.

FIGS. 6A to 6C are schematic diagrams showing a configuration of apiezoelectric vibrating element according to a second embodiment of theinvention, FIG. 6A is a plan view, FIG. 6B is a cross-sectional view ofline P-P, and FIG. 6C is a cross-sectional view of line Q-Q.

FIGS. 7A to 7C are schematic diagrams showing a configuration of apiezoelectric vibrating element according to a third embodiment of theinvention, FIG. 7A is a plan view, FIG. 7B is a cross-sectional view ofline P-P, and FIG. 7C is a cross-sectional view of line Q-Q.

FIG. 8A is a plan view showing a configuration of a modification exampleof the piezoelectric vibrating element, and FIG. 8B is a plan viewshowing a configuration of a modification example of the piezoelectricvibrating elements.

FIG. 9 is a plan view showing a configuration of a modification exampleof the piezoelectric vibrating element.

FIG. 10 is a manufacturing process diagram of a piezoelectric substrate.

FIG. 11 is a manufacturing process diagram of an excitation electrodeand a lead electrode of a piezoelectric vibrating element.

FIG. 12A is a plan view of respective recesses formed on a quartzcrystal wafer, and FIGS. 12B to 12E are cross-sectional views of each ofthe recesses in the X-axis direction.

FIG. 13A is a plan view of respective recess formed on a quartz crystalwafer, and FIGS. 13B to 13E are cross-sectional views of each of therecesses in the Z′-axis direction.

FIG. 14A is a perspective view of the piezoelectric vibrating elementshown in FIGS. 1A to 1F, and FIG. 14B is a vertically cross-sectionalview of the line Q-Q (showing only the cut surface).

FIG. 15A is a plan view of a piezoelectric resonator, and FIG. 15B is avertically cross-sectional view thereof.

FIG. 16 is a vertically cross-sectional view of an electronic device(piezoelectric device).

FIG. 17A is a plan view of an electronic device (piezoelectric device),and FIG. 17B is a vertically cross-sectional view thereof.

FIG. 18 is a vertically cross-sectional view of a modification exampleof an electronic device (piezoelectric device).

FIG. 19 is a pattern diagram of an electronic apparatus.

FIG. 20 is a perspective view showing a configuration of a portable typepersonal computer as an example of the electronic apparatus.

FIG. 21 is a perspective view showing a configuration of a mobiletelephone as another example of the electronic apparatus.

FIG. 22 is a perspective view showing a configuration of a digital stillcamera as another example of the electronic apparatus.

FIG. 23 is a perspective view showing a configuration of a vehicle as anexample of a mobile object.

FIGS. 24A to 24C are configuration descriptive diagrams of apiezoelectric substrate according to a modification example.

FIGS. 25A, 25B and 25C are configuration descriptive diagrams of apiezoelectric substrate according to another modification example.

FIGS. 26A to 26C show a modification example of the piezoelectricvibrating element, FIG. 26A is a plan view thereof, FIG. 26B is anenlarged view of the main sections, and FIG. 26C is a cross-sectionalview of the main sections.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described in detailwith reference to the drawings.

First Embodiment

FIGS. 1A to 1F are schematic diagrams showing a configuration of apiezoelectric vibrating element 1 according to a first embodiment of theinvention. FIG. 1A is a plan view of the piezoelectric vibrating element1, FIG. 1B is a cross-sectional view of cross-section P-P taken from the+X-axis direction, FIG. 1C is a cross-sectional view of cross-sectionQ-Q taken from the −Z′-axis direction, FIGS. 1D, 1E, and 1F arecross-sectional view of cross-section Q-Q showing modification examplesof a slit shape.

The piezoelectric vibrating element 1 includes a vibrating section 12that includes a thin rectangular vibration area, a piezoelectricsubstrate 10 that is formed integrally with the vibrating section 12 andhas a thick section 13 of which the thickness is greater than that ofthe vibration area, excitation electrodes 25 a and 25 b that arerespectively disposed on the front and rear surfaces of the vibrationarea so as to oppose each other, and lead electrodes 27 a and 27 b thatare provided respectively extending from each of the excitationelectrodes 25 a and 25 b to pad electrodes 29 a and 29 b provided in thethick section 13.

Herein, the piezoelectric substrate 10 includes the vibrating section 12including the vibration area and the circumferential edge and the thicksection 13. In addition, the ratio between the dimensions of thevibrating section 12 in the X-axis direction and the dimensions of thevibrating section 12 in the Z′-axis direction is 1.26:1 as is known.

In addition, the vibrating area is the area in which the vibratingenergy is trapped, and the circumferential edge is the circumferentialarea of the vibrating area in the vibrating section 12.

The piezoelectric substrate 10 is a rectangular shape, and includes thevibrating section 12 that is thin and plate-like, a first thick section14 that is disposed along a side 12 a that is one side of the four sidesof the vibrating section 12, and a second thick section 15 that isdisposed along a side 12 b that is another side adjoining the side 12 aof the vibrating section 12. In other words, the piezoelectric substrate10 includes an L-shaped thick section (thick support section) 13 (thefirst thick section 14 and the second thick section 15) integrallyformed along the adjoining sides 12 a and 12 b of the vibrating section12.

The first thick section 14 includes a first inclined section 14 b thatis continuously formed from the side 12 a of the vibrating section 12and of which the thickness gradually increases as the first inclinedsection is separated beginning from one edge (inner edge) coming intocontinuous contact with the side 12 a of the vibrating section 12 towardthe other edge (outer edge) and a first thick section main body 14 a ofa thick quadrangle column shape coming into continuous contact with theother edge (outer edge) of the first inclined section 14 b.

In the same manner, the second thick section 15 includes a secondinclined section 15 b that is continuously formed from the side 12 b ofthe vibrating section 12 and of which the thickness gradually increasesas the second inclined section is separated beginning from one edge(inner edge) coming into continuous contact with the side 12 b of thevibrating section 12 toward the other edge (outer edge) and a secondthick section main body 15 a of a thick quadrangle column shape cominginto continuous contact with the other edge (outer edge) of the secondinclined section 15 b.

Furthermore, the first thick section main body 14 a and the second thicksection main body 15 a are referred to areas with a fixed thickness inthe Y′-axis direction.

Respective main planes (front surfaces) of the first thick section 14and the second thick section 15 are formed further protruding than onemain plane (front surface) of the vibrating section 12, and the othermain plane (rear surface) of the vibrating section 12 and respective theother main planes (rear surfaces) of the first thick section 14 and thesecond thick section 15 are disposed on the same plane, in other words,a plane parallel with the X-Z′ plane of the coordinate axis shown inFIGS. 1A to 1F. The above-described one main plane (front surface) isalso called a recessed surface, and the other main plane (rear surface)is also called a flat surface (plane surface).

One main plane (front surface) of the first thick section 14 is formedfurther protruding than one main plane (front surface) of the vibratingsection 12. In addition, the other main plane (rear surface) of thefirst thick section 14 comes into continuous contact with the other mainplane (rear surface) of the vibrating section 12 so as to form the samesurface. Furthermore, even when there is an energy trapped regionprotruding from the mesa in the vibration area, it may be preferablethat the other main plane (rear surface) of the circumferential edgecomes into continuous contact with the other main plane of the firstthick section 14 so as to form the same surface.

One main plane (front surface) of the second thick section 15 is formedfurther protruding than one main plane (front surface) of the vibratingsection 12. In addition, the other main plane (rear surface) of thesecond thick section 15 comes into continuous contact with the othermain plane (rear surface) of the vibrating section 12 so as to form thesame surface. Furthermore, even when there is an energy trapped regionprotruding from the mesa in the vibration area, it may be preferablethat the other main plane (rear surface) of the circumferential edgecomes into continuous contact with the other main plane of the secondthick section 15 so as to form the same surface.

In this way, the first thick section 14 is provided in the +X directionon the X-axis, and the second thick section 15 is provided in the Z′direction on the Z′-axis.

In the first thick section 14, at least one slit 20 for easing stressaccompanied by mounting of the piezoelectric vibrating element 1 isformed between the vibrating section 12 and the pad electrodes 29 a and29 b extending along the Z′-axis direction so as to penetrate in theY′-axis direction. In the embodiment shown in FIGS. 1A to 1F, the slit20 is formed in the inner side of a surface of the first thick sectionmain body 14 a along the boundary (contact portion) of the firstinclined section 14 b and the first thick section main body 14 a. Inother words, the slit 20 is formed surrounded by the first thick sectionmain body 14 a.

Furthermore, the slit 20 is not limited to one formed in a penetratingmanner as shown in FIG. 1C, and may be a groove-like slit having abottom. To describe such a groove-like slit in more detail, as shown inFIG. 1D, for example, it may be configured as slits provided in bothfront and rear surfaces as a first slit 20 a that is formed from thefront surface side of the first thick section main body 14 a having abottom and a second slit 20 b that is formed from the rear surface sideof the first thick section main body 14 a having a bottom.

In addition, as shown in FIG. 1E, it may be configured as a third slit20 c that is formed from the front surface side of the first thicksection main body 14 a having a bottom. In addition, as shown in FIG.1F, it may be configured as a fourth slit 20 d that is formed from therear surface side of the first thick section main body 14 a having abottom.

In addition, the thickness of the bottoms of the slits 20 a, 20 b, 20 c,and 20 d may be thicker or thinner than the thickness of the vibratingsection 12.

The shape of the slit 20 (20 a, 20 b, 20 c, and 20 d) described hereincan be applied to other embodiments, modification examples, andapplication examples to be described below.

The piezoelectric substrate 10 is a quartz crystal substrate of which apiezoelectric material belongs to a trigonal system, and has crystalaxes X, Y, and Z orthogonal to one another as shown in FIG. 2. The Xaxis, Y axis, and Z axis are respectively referred to as an electricalaxis, a mechanical axis, and an optical axis. In addition, with regardto the quartz crystal substrate, a plate cut out from quartz crystalalong a plane obtained by rotating the X-Z plane around the X axis by apredetermined angle of θ, that is, a plate of a rotation Y cut quartzcrystal substrate is used for a piezoelectric vibrating element. Whenthe rotation Y cut quartz crystal substrate is an AT cut quartz crystalsubstrate, for example, the angle θ is about 35° 15′. Furthermore,respective Y′ axis and Z′ axis are obtained by rotating the Y axis and Zaxis around the X axis by θ. Thus, the AT cut quartz crystal substratehas crystal axes X, Y′, and Z′ orthogonal to one another. In addition,the thickness direction is the Y′ axis, the X-Z′ plane (a planeincluding the X and Z′ axes) orthogonal to the Y′ axis is the mainplane, and thickness shear vibration is excited as the main vibration.

In other words, when an axis obtained by inclining the Z axis toward the−Y direction of the Y axis is set to be the Z′ axis and an axis obtainedby inclining the Y axis toward the +Z direction of the Z axis is set tobe the Y′ axis with respect to the X axis of the orthogonal coordinatesystem including the X axis (electrical axis), the Y axis (mechanicalaxis), and the Z axis (optical axis) as shown in FIG. 2, thepiezoelectric substrate 10 is an AT cut quartz crystal substrateincluding a plane parallel to the X axis and the Z′ axis and havingthickness in the direction parallel to the Y′ axis.

As shown in FIG. 1A, the piezoelectric substrate 10 has a rectangularshape with a thickness in the direction parallel to the Y′ axis(hereinafter, referred to as the “Y′-axis direction”), a long side inthe direction parallel to the X axis (hereinafter, referred to as the“X-axis direction”), and a short side in the direction parallel to theZ′ axis (hereinafter, referred to as the “Z′-axis direction”).

Furthermore, the shape of the piezoelectric substrate 10 is not limitedto a rectangle, and may be a square, or other quadrangle, or a polygonincluding a pentagon or one having more number of sides. In addition,one side of the vibrating section is not limited to a straight line, andmay be one including a curve, and when the external shape of thevibrating section is a polygon, at the corner between the one side andanother side connected thereto, another side may be provided.

In addition, the piezoelectric substrate according to the embodiment ofthe invention is not limited to AT cut with the angle θ of about 35°15′, and it is needless to say that the invention can be broadly appliedto a piezoelectric substrate of BT cut, or the like, in which thicknessshear vibration is excited.

The excitation electrodes 25 a and 25 b for driving the piezoelectricsubstrate 10 are quadrangle shapes in the embodiment shown in FIGS. 1Ato 1F, and formed on both front and rear surfaces (both upper and lowersurfaces) substantially at the center of the vibrating section 12 so asto oppose each other via the piezoelectric substrate 10. The size of theexcitation electrode 25 b in the rear surface (flat surface) side is setto be sufficiently larger than the size of the excitation electrode 25 ain the front surface (recessed surface) side. This is for not setting anenergy trapping coefficient according to a mass effect of the excitationelectrodes 25 a and 25 b to be higher than necessary. In other words, bysetting the excitation electrode 25 b in the rear surface (flat surface)side to be sufficiently large, a plate back amount Δ (=(fs−fe)/fs,wherein fs is a cut-off frequency of the piezoelectric substrate and feis a frequency when an excitation electrode is attached on the entiresurface of the piezoelectric substrate) depends only on the mass effectof the excitation electrode 25 a in the front surface (upper surface)side.

The excitation electrodes 25 a and 25 b are formed in such a way of, forexample, forming a film with nickel (Ni) on a base and then forming afilm with gold (Au) thereon in an overlapping manner, using a vapordeposition device, a sputtering device, or the like. With regard to thethickness of gold (Au), it is desirable that only the main vibration(S0) is set to be in a trapping mode, and oblique symmetric inharmonicmodes (A0, A1, . . . ) and symmetric inharmonic modes (S1, S3, . . . )are set not to be in a trapping mode in a range where ohmic loss doesnot increase. However, if the films are formed so as to avoid ohmic lossof the electrode film thickness in an attempt to configure apiezoelectric vibrating element of an extremely high frequency band of490 MHz, shifting a low-order inharmonic mode to a trapping mode cannotbe avoided.

The lead electrode 27 a formed on the front surface side extending fromthe excitation electrode 25 a is conductively connected to the padelectrode 29 a formed on the front surface of the first thick sectionmain body 14 a via the second inclined section 15 b and the second thicksection main body 15 a starting on the front surface of the vibratingsection 12. In addition, the lead electrode 27 b formed on the rearsurface side extending from the excitation electrode 25 b isconductively connected to the pad electrode 29 b formed on the rearsurface of the first thick section main body 14 a via thecircumferential edge on the rear surface of the piezoelectric substrate10.

The embodiment shown in FIG. 1A is an example of a pull-outconfiguration of the lead electrodes 27 a and 27 b, and the leadelectrode 27 a may pass through other thick section. However, thelengths of the lead electrodes 27 a and 27 b are desirable to be theshortest, and it is desirable to consider the lead electrodes 27 a and27 b not intersecting each other when interposing the piezoelectricsubstrate 10 so that an increase of electrostatic capacity issuppressed.

In addition, the embodiment shown in FIGS. 1A to 1F shows an example inwhich respective pad electrodes 29 a and 29 b are formed opposing thefront and rear surfaces of the piezoelectric substrate 10. When thepiezoelectric vibrating element 1 is contained in a package, thepiezoelectric vibrating element 1 is turned over, the pad electrode 29 ais mechanically fixed and electrically connected to an element-mountingpad of the package with a conductive adhesive, and the pad electrode 29b is electrically connected to an electrode terminal of the package byusing a bonding wire, as described below. In this way, if a portionsupporting the piezoelectric vibrating element 1 is set at one point, itis possible to reduce stress caused by such a conductive adhesive.

The reason of providing the slit 20 between the vibrating section 12 andthe pad electrodes 29 a and 29 b that are supported sections by thepiezoelectric vibrating element 1 is to prevent the expansion of stressarising during hardening of the conductive adhesive.

In other words, when the piezoelectric vibrating element 1 is adheredand fixed to the package with the conductive adhesive, first, theconductive adhesive is applied to the pad electrode (supported section)29 a of the first thick section main body 14 a and the electrode ismounted on an element-mounting pad of the package, or the like, and thenweight is exerted thereon. The package is left at a high temperature fora predetermined time in order to harden the conductive adhesive. In astate of a high temperature, since both the first thick section mainbody 14 a and the package extend, and the adhesive is temporarilysoftened, stress does not arise in the first thick section main body 14a. When the conductive adhesive is hardened, the first thick sectionmain body 14 a and the package is cooled and then the temperaturereturns to the normal temperature (25° C.), stress caused by thehardened conductive adhesive arises due to differences between therespective linear expansion coefficients of the conductive adhesive, thepackage, and the first thick section main body 14 a. Stress expands fromthe first thick section main body 14 a to the second thick section 15,and from the first inclined section 14 b and the second inclined section15 b to the vibrating section 12. In order to prevent stress fromexpanding, the slit 20 for easing stress is provided.

In this way, since the slit 20 is disposed along the boundary(continuous contact portion) of the first inclined section 14 b and thefirst thick section main body 14 a, a large area of the pad electrode 29a of the first thick section main body 14 a can be secured, and adiameter of the conductive adhesive to be applied can be set to belarge. On the contrary, if the slit 20 is disposed closer to the padelectrode 29 a of the first thick section main body 14 a, the area ofthe pad electrode 29 a becomes narrower, and a diameter of theconductive adhesive has to be set to be small. As a result, an absoluteamount of conductive filler contained in the conductive adhesive is alsoreduced, conductivity deteriorates, a resonant frequency of thepiezoelectric vibrating element 1 becomes unstable, whereby there is aconcern that frequency fluctuation (generally referred to as F jump)tends to occur.

Therefore, it is preferable that the slit 20 be disposed along theboundary (continuous contact portion) of the first inclined section 14 band the first thick section main body 14 a.

In order to obtain distribution of stress (∝ strain) arising in thepiezoelectric substrate 10, a simulation is conducted generally using afinite element method. As stress on the vibrating section 12 getssmaller, a piezoelectric vibrating element excellent in afrequency-temperature characteristic, frequency reproducibility, afrequency aging characteristic, and the like is obtained.

As the conductive adhesive, a silicon-based, an epoxy-based, apolyimide-based, a bismaleimide-based adhesive, or the like is generallyused, but considering a frequency temporal change of the piezoelectricvibrating element 1 caused by degassing, a polyimide-based conductiveadhesive was used.

Since the polyimide-based conductive adhesive is hard, the amount ofgenerated stress can be reduced further by supporting one spot than bysupporting two separate spots (two-point support). For this reason, thepiezoelectric vibrating element 1 for a voltage controlled crystaloscillator (VCXO) of a high frequency band of 100 to 500 MHz, forexample, 490 MHz employed the configuration of one spot support(one-point support).

In other words, as described below, the pad electrode 29 a ismechanically fixed to and electrically connected to the element-mountingpad of the package using the conductive adhesive, and the other padelectrode 29 b is electrically connected to the electrode terminal ofthe package using a bonding wire.

In addition, the external shape of the piezoelectric substrate 10 shownin FIGS. 1A to 1F is so-called X-long in which the length thereof in theX-axis direction is longer than the length thereof in the Z′-axisdirection. With regard to this matter, stress arises when thepiezoelectric substrate 10 is adhered and fixed with the conductiveadhesive, or the like, however, as well-known, if a frequency changewhen pressure is exerted on both ends of the AT cut quartz crystalsubstrate in the X-axis direction is compared to a frequency change whenthe same pressure is exerted on both ends thereof in the Z′-axisdirection, the frequency change when the pressure is exerted on bothends thereof in the Z′-axis direction is smaller. In other words, it ispreferable that a support point be provided along the Z′-axis directionas the frequency change caused by stress is smaller.

FIG. 3A is a plan view showing the disposition and configuration of thelead electrodes 27 a and 27 b and the pad electrodes 29 a and 29 bformed on the front and rear surfaces of the piezoelectric substrate 10,and FIG. 3B is a plan view showing the disposition and configuration ofthe excitation electrodes 25 a and 25 b.

On the front and rear surfaces of the piezoelectric substrate 10, thelead electrode 27 a extends from the circumferential edge of theexcitation electrode 25 a that is assumed to be the front surface of thepiezoelectric substrate 10 and passes through the front surface of thesecond thick section 15 so as to be formed continuous to the padelectrode 29 a provided substantially at the center of the front surfaceof the first thick section main body 14 a. In addition, the leadelectrode 27 b extends from the circumferential edge of the excitationelectrode 25 b that is assumed to be the rear surface of thepiezoelectric substrate 10 along the circumference of the rear surface(flat surface) so as to be formed continuous to the pad electrode 29 bprovided substantially at the center of the rear surface of the firstthick section main body 14 a.

The lead electrodes 27 a and 27 b are respectively provided with a firstlayer composed of a thin film of chrome (Cr) and a second layer composedof a thin film of gold (Au) laminated on the upper surface of the firstlayer. A view taken by enlarging cross-section R-R of a part 27A of thelead electrode 27 a is shown in the dashed circle 27A in the left sideof FIG. 3A. The lead electrode 27 a is configured such that a chromicthin film 27 c on the front surface (upper surface) side of the firstthick section main body 14 a is set as a base and a gold thin film 27 gis formed thereon in a laminating manner. The laminating manner for thelead electrode 27 b is the same.

The pad electrodes 29 a and 29 b provided on the front and rear surfacesof the middle section of the first thick section main body 14 a includea first layer being made of chromic (Cr) thin film and a second layerbeing made of the gold (Au) thin film which is laminated on the uppersurface of the first layer. A enlarged cross-sectional view ofcross-section T-T of a part 29A of the pad electrodes 29 a and 29 b, isshown in the broken line circle 29A of the middle lower section of theFIG. 3A. On the front surface side (upper surface side) of the firstthick section main body 14 a, the pad electrode 29 a is configured bysetting a chromic (Cr) thin film 29 c as a base sheet and laminating agold (Au) thin film 29 g for film formation on thereof. The laminatingmanner for the pad electrode 29 b is the same.

Since the lead electrodes 27 a and 27 b and the pad electrodes 29 a and29 b are formed in the same process, as an example of the filmthicknesses, the chromic (Cr) thin film of the first layer is formed tohave the thickness of 100 Å (1 Å is 0.1 nm (nanometer)) and the goldthin film is formed to have the thickness of 2000 Å. For this reason,ohmic loss of the lead electrodes 27 a and 27 b and the pad electrodes29 a and 29 b is not incurred, and bonding strength is also sufficient.

Furthermore, it may be configured to interpose other metal film betweenthe chromic (Cr) thin film and the gold (Au) thin film.

FIG. 3B is a plan view showing the disposition and configuration of theexcitation electrodes 25 a and 25 b formed on the piezoelectricsubstrate 10 so as to match the lead electrodes 27 a and 27 b formed inthe previous process. The excitation electrode 25 a is formed on thefront surface side of the vibrating section 12, and the excitationelectrode 25 b is formed on the rear surface (flat surface) side so thatthe size thereof is sufficiently larger than that of the excitationelectrode 25 a and the excitation electrode 25 a is settled in the areaof the excitation electrode 25 b.

Herein, in the formation of the excitation electrodes 25 a and 25 b, theexcitation electrodes 25 a and 25 b are formed so as to overlap at leastpart of the lead electrodes 27 a and 27 b formed beforehand in theprevious process. As shown in FIG. 3B, for example, the excitationelectrode 25 a has a part 27 d of the lead electrode extending from anedge portion. The part 27 d of the lead electrode is configured tooverlap the front surface of the lead electrode 27 a. With theconfiguration, the excitation electrode 25 a can be assuredlyelectrically connected to the lead electrode 27 a and accordingly,conduction failure can be prevented. The excitation electrode 25 bformed on the rear surface (flat surface) side is configured in the samemanner.

Alternatively, a part of the lead electrode 27 b formed beforehand inthe previous process may be formed so as to enter (overlap) the area ofthe excitation electrode 25 b. In this case, since a plate back amountused for determining a resonance frequency depends only on a mass effectof the excitation electrode 25 a formed on one main plane that is thefront surface side of the vibrating section 12, a part of the leadelectrode 27 b is configured to be positioned on the outer circumferenceside than the external shape of the excitation electrode 25 a so thatthe part thereof does not overlap in a plan view while interposing thepiezoelectric substrate 10 with the excitation electrode 25 a andthereby not changing the plate back amount from the designed value.

In an example of a configuration of the excitation electrodes 25 a and25 b, a first layer composed of a thin film of nickel (Ni) and a secondlayer composed of a thin film of gold (Au) laminated on the uppersurface of the first layer are provided. Part of the excitationelectrodes 25 a and 25 b in cross-section U-U in the dashed circle isshown in the dashed circle of the right side in FIG. 3B. On the frontand rear surfaces of the vibrating section 12, thin films 25 n of nickel(Ni) are formed as first layers and thin films 25 g of gold (Au) areformed as second layers in a laminating manner. As an example of thefilm thickness, the nickel (Ni) film thickness of as the first layer is70 Å, and the gold (Au) film thickness is 600 Å.

Furthermore, it may be configured to interpose other metal film betweenthe nickel (Ni) thin film and the gold (Au) thin film.

The reason that the respective electrode materials and electrodethicknesses of the lead electrodes 27 a and 27 b and the pad electrodes29 a and 29 b, and the excitation electrodes 25 a and 25 b are differentfrom each other when a fundamental frequency of the vibrating section 12of the piezoelectric substrate 10 is set to be 490 MHz that is anextremely high frequency band will be described below. Let us assumethat the lead electrodes 27 a and 27 b, the pad electrodes 29 a and 29 band the excitation electrodes 25 a and 25 b are configured to include,for example, a thin film of nickel (Ni) with 70 Å as a first layer and athin film of gold (Au) with 600 Å as a second layer. The main vibrationis sufficiently in a trapping mode, and crystal impedance (CI,equivalent resistance) thereof becomes small, but since the gold (Au)film thickness of the lead electrodes 27 a and 27 b is thin, there isconcern that ohmic loss of the thin film occurs. Furthermore, if the padelectrodes 29 a and 29 b are formed of a nickel (Ni) thin film with 70 Åand a gold (Au) thin film with 600 Å, there is concern that insufficientstrength of wire bonding occurs.

In addition, if the lead electrodes 27 a and 27 b, the pad electrodes 29a and 29 b and the excitation electrodes 25 a and 25 b are composed of,for example, a thin film of chrome (Cr) with 70 Å as a first layer and athin film of gold (Au) with 600 Å as a second layer, heat causes chrome(Cr) to diffuse into the thin film of gold (Au) as the thin film of gold(Au) is thin, resulting in ohmic loss of the thin film, and therefore,there is concern that a CI of the main vibration increases.

Thus, in the embodiment, formation processes of the lead electrodes 27 aand 27 b, the pad electrodes 29 a and 29 b and the excitation electrodes25 a and 25 b are separated, and materials and film thicknesses ofrespective electrode thin films are set so as to be optimum for thefunctions of the respective thin films. In other words, for theexcitation electrodes 25 a and 25 b, for example, the electrode filmthicknesses were set to be as thin as 70 Å for nickel (Ni) and 600 Å forgold so that the main vibration is in the trapping mode, a proximateinharmonic mode is shifted to a propagation mode (non-trapping mode) aspossible. On the other hand, for the lead electrodes 27 a and 27 b andthe pad electrodes 29 a and 29 b, the film thickness of chrome (Cr) wasset to be 100 Å and the film thickness of gold (Au) to be 2000 Å so thatfilm resistance of a thin lead electrode is reduced, and the strength ofbonding increases.

The above-described film thicknesses are examples, and the values arenot limited. For the excitation electrodes 25 a and 25 b, the laminatedfilms of nickel (Ni) and gold (Au) with the optimum film thickness areused in consideration of the energy trapping theory and ohmic loss ofthe thin film. In addition, for the lead electrodes 27 a and 27 b andthe pad electrodes 29 a and 29 b, the laminated films of chrome (Cr) andgold (Au) with the necessary thickness are used in consideration ofohmic loss of the thin film and the strength of bonding.

A method for manufacturing the excitation electrodes 25 a and 25 b, thelead electrodes 27 a and 27 b, and the pad electrodes 29 a and 29 b willbe described later.

In an embodiment of FIGS. 1A to 1F, a quadrangle, that is a square or arectangle (having a long side in the X-axis direction) is exemplified asthe shape of the excitation electrodes 25 a and 25 b, but the shape isnot limited hereto. In the example shown in FIG. 4, the excitationelectrode 25 a on the front surface side has a circular shape and theexcitation electrode 25 b on the rear surface side has a quadrangleshape of which the area is sufficiently larger than that of theexcitation electrode 25 a. Furthermore, the excitation electrode 25 b onthe rear surface side may have a circular shape of which the area issufficiently large.

In an embodiment shown FIG. 5, the excitation electrode 25 a on thefront surface side has an elliptical shape and the excitation electrode25 b on the rear surface side has a quadrangle shape of which the areais sufficiently larger than that of the excitation electrode 25 a. Asquartz crystal has different displacement distributions in the X-axisdirection and in the Z′-axis direction due to anisotropy of an elasticconstant, a cut plane obtained by cutting displacement distribution by aplane parallel to the X-Z′plane is an elliptical shape. For this reason,when the excitation electrode 25 a in an elliptical shape is used, thepiezoelectric vibrating element 1 can be driven showing the highestefficiency. In other words, a capacity ratio 7 of the piezoelectricvibrating element 1 (=C0/C1, wherein C0 is electrostatic capacity, andC1 is series resonance capacity) can be set to the minimum level. Inaddition, the excitation electrode 25 a may be an oval shape.

Second Embodiment

FIGS. 6A to 6C are schematic diagrams showing a configuration of apiezoelectric vibrating element 2 according to a second embodiment. FIG.6A is a plan view of the piezoelectric vibrating element 2, FIG. 6B isacross-sectional view of cross-section P-P taken from the +X-axisdirection and FIG. 6C is a cross-sectional view of cross-section Q-Qtaken from the −Z′-axis direction.

A difference of the piezoelectric vibrating element 2 from thepiezoelectric vibrating element 1 shown in FIGS. 1A to 1F is theposition where the slit 20 for easing stress is provided. In the presentembodiment, the slit 20 is formed within the first inclined section 14 bas being separated from the circumferential edge of the side 12 a of thethin vibrating section 12. The slit 20 is not formed within the firstinclined section 14 b so that one circumferential edge of the slit 20comes into contact with the side 12 a along the side 12 a of thevibrating section 12, but provided being separated from bothcircumferential edges of the first inclined section 14 b. That is, inthe first inclined section 14 b, an extremely thin inclined section 14bb is left which comes into continuous contact with the circumferentialedge of the side 12 a of the vibrating section 12. In other words, theextremely thin inclined section 14 bb is formed between the side 12 aand the slit 20.

The reason of leaving the extremely thin inclined section 14 bb is asfollows. That is, if the vibrating section 12 is excited by applyinghigh frequency voltage to the excitation electrodes 25 a and 25 bdisposed in the vibrating section 12, inharmonic modes (A0, S1, A1, S2 .. . ) are excited in addition to the main vibration (S0). A desirablemanner is to set a trapping mode only for the mode of the main vibration(S0) and a propagation mode (non-trapping mode) for other inharmonicmodes. However, if the vibrating section 12 is thin and the fundamentalfrequency thereof is set to several hundred MHz, it is necessary toincrease the thicknesses of the excitation electrodes 25 a and 25 b to acertain level in order to avoid ohmic loss of the electrode films. Forthis reason, when the thicknesses of the excitation electrodes 25 a and25 b are set to a certain level or higher, a low-order inharmonic modeproximate to the main vibration is shifted to a trapping mode. As aresult, the shapes of both circumferential edges of the vibratingsection 12 of FIGS. 6A to 6C in the Z′-axis direction are asymmetric,and the shapes of both circumferential edges thereof in the X-axisdirection are asymmetric, and accordingly, the amplitude of a stationarywave in a low-order inharmonic mode is suppressed.

Third Embodiment

FIGS. 7A to 7C are schematic diagrams showing a configuration of apiezoelectric vibrating element 3 according to a third embodiment. FIG.7A is a plan view of the piezoelectric vibrating element 3, FIG. 7B isacross-sectional view of cross-section P-P taken from the +X-axisdirection, and FIG. 7C is a cross-sectional view of cross-section Q-Qtaken from the −Z′-axis direction.

A difference of the piezoelectric vibrating element 3 from thepiezoelectric vibrating element 1 shown in FIGS. 1A to 1F is that twoslits for easing stress are provided such that a first slit 20 e isprovided within a plane of the first thick section main body 14 a and asecond slit 20 f is formed within a plane of the first inclined section14 b. The purpose of providing respective individual slits within theplanes of the first thick section main body 14 a and the first inclinedsection 14 b is that, by providing two slits within the first thicksection 14, expansion of stress arising during hardening of a conductiveadhesive can be more effectively suppressed. Since the detail on thematter has already been described above, so it is omitted herein.

FIG. 8A is a plan view showing a configuration of a modification exampleof the piezoelectric vibrating element 3 shown in FIGS. 7A to 7C. In apiezoelectric vibrating element 3′, the first slit 20 e is providedwithin a plane of the first thick section main body 14 a and the secondslit 20 f is provided within a plane of the first inclined section 14 b.However, there is a different from the piezoelectric vibrating element 3in that the first slit 20 e and the second slit 20 f are not disposed inparallel to each other in the X-axis direction as shown in the plan viewof FIG. 7A, but disposed so as to be displaced from each other by astep-difference thereby being separated from each other in the Z′-axisdirection. By providing two slits of the first slit 20 e and the secondslit 20 f, an effect of preventing stress caused by a conductiveadhesive from expanding to the vibrating section 12 can be improved.

FIG. 8B is a plan view showing a configuration of a modification exampleof the piezoelectric vibrating elements 1 and 2 according to the firstand the second embodiments shown in FIGS. 1A to 1F and FIGS. 6A to 6C.In a piezoelectric vibrating element 1′, the slit 20 is formed crossingthe areas of the first thick section main body 14 a and the firstinclined section 14 b. By providing the slit 20 in this way, an effectof satisfying the configurations of the piezoelectric vibrating elements1 and 2 at the same time can be expected, and the effect of preventingstress caused by a conductive adhesive from expanding to the vibratingsection 12 can be improved.

FIG. 9 is a plan view showing a configuration of a modification exampleof the piezoelectric vibrating element 1 of the embodiment shown inFIGS. 1A to 1F. In the piezoelectric vibrating element 1″, the leadelectrode 27 a is formed so as to extend from a circumferential edge ofthe excitation electrode 25 a on the front surface, pass through thefront surface of the second thick section 15, and be continuouslyconnected to the pad electrode 29 a provided on the front surface on theleft side of the center of the first thick section main body 14 a. Inaddition, the lead electrode 27 b is formed so as to extend from acircumferential edge of the excitation electrode 25 b on the rearsurface, pass through an edge of the rear surface and thecircumferential edge of the piezoelectric substrate 10 where the rearsurface comes into continuous contact with the front surface, and bearranged continuous to the pad electrode 29 b provided on the frontsurface on the right side of the center of the first thick section mainbody 14 a.

The difference from the piezoelectric vibrating element 1 of theembodiment shown in FIGS. 1A to 1F is the positions where the padelectrodes 29 a and 29 b are disposed. The pad electrodes 29 a and 29 bof a piezoelectric vibrating element 1″ are provided being separatedfrom each other on the front surface of the first thick section mainbody 14 a. The pad electrode 29 b includes a conductor thin filmcrossing a circumferential edge of the piezoelectric substrate 10 so asto be electrically connected to the lead electrode 27 b formed on therear surface. The pad electrodes 29 a and 29 b are configured so as toachieve easy electric conduction when a conductive adhesive is appliedonto the pad electrodes 29 a and 29 b on the front surface side and thesubstrate is reversed so as to be mounted on an element-mounting pad ofa package.

In other words, the configuration of the modification example of FIG. 9intends to achieve electric conduction, support and fixation by applyinga conductive adhesive to two spots (two points) of the first thicksection 14 on one surface (front surface) of the piezoelectric vibratingelement 1″. The configuration is suitable for lowering the height, butthere is concern that stress caused by the conductive adhesive slightlyincreases. Thus, by employing a piezoelectric vibrating element providedwith two slits as shown in the piezoelectric vibrating elements 3 and 3′according to the third embodiment, it is expected to suppress theinfluence of stress arising during hardening of the conductive adhesiveon a vibration area.

Alternatively, when the hardness of the conductive adhesive isrelatively high, there is also a technique of reducing strain (stress)relating to mounting that occurs between the centers of the two pointsby narrowing the interval between the centers of the “two spots (twopoints)” to which the conductive adhesive is applied. On the other hand,when the hardness of the conductive adhesive is relatively low, there isalso a technique of reducing strain (stress) relating to mounting thatoccurs between the center of the two points by using a silicon-basedadhesive so as to cause the conductive adhesive to have a bufferingproperty.

FIG. 10 is a manufacturing process diagram relating to the vibratingsection 12 of the piezoelectric substrate 10, an external shape thereof,and formation of the slit 20. Herein, a quartz crystal wafer isexemplified as a piezoelectric wafer and the drawing only shows across-section of the plane Y′-Z′.

In Step S1, a quartz crystal wafer 10W having a predetermined thicknessof, for example, 80 μm and both surfaces that have undergone polishingis sufficiently cleaned, dried, and then, respective metal films(corrosion-proof film) M are formed in such a manner of having a chrome(Cr) film to be formed as the base and a gold (Au) film to be laminatedthereon by performing sputtering, or the like for the front and rearsurfaces of the wafer.

In Step S2, photoresist films (referred to as resist films) R areapplied onto both surfaces of the metal films M formed as the front andrear surfaces.

In Step S3, a portion of the resist film R corresponding to thevibrating section 12 (recess) on the front surface is exposed to lightby using a light exposure apparatus and a mask pattern. After theexposed resist film R is developed and then peeled, the metal film M atthe position corresponding to the vibrating section 12 on the frontsurface is exposed. When the metal film M exposed from the resist film Ris melted using a solution such as aqua regia and then removed, a quartzcrystal plane at the position corresponding to the vibrating section 12on the front surface is exposed.

In Step S4, the exposed quartz crystal plane is etched from the frontsurface side using a mixed solution of hydrofluoric acid (fluorinatedacid) and ammonium fluoride until the portion has a desired thickness.

In Step S5, the resist films R on both surfaces are peeled using apredetermined solution and the further exposed metal films M on bothsurfaces are removed using aqua regia, or the like. In the quartzcrystal wafer 10W in the stage, the recess formed at the positioncorresponding to the vibrating section 12 on the front surface (onesurface) is in a state of being regularly arranged in a grid shape.

In Step S6, metal films M (Cr+Au) are formed on both surfaces of thequartz crystal wafer 10W obtained in Step S5.

In Step S7, respective resist films R are coated on both surfaces of themetal films M (Cr+Au) formed in Step S6.

In Step S8, by using a light exposure apparatus and a predeterminedmask, respective resist films R at the position corresponding to theexternal shape of the piezoelectric substrate 10 and the slit 20 (notshown in the drawing) are exposed to light from both front and rearsurfaces and developed, and then respective resist films R are peeled.Furthermore, the exposed metal films M are removed after being melt witha solution such as aqua regia, or the like.

In Step S9, the exposed quartz crystal planes are etched using a mixedsolution of hydrofluoric acid (fluorinated acid) and ammonium fluorideso as to form the external shape of the piezoelectric substrate 10 andthe slit 20. Furthermore, when the slit 20 is to be formed havingrespective bottom portions (refer to FIG. 1D) from both front and rearsurface sides of the quartz crystal wafer 10W, the slit can be formed byusing a change in an etching rate, or the like, occurring when thewidths of the resist films R at the position corresponding to the slit20 are reduced.

In Step S10, the remaining resist films R are peeled and the exposedmetal films are melted and then removed. In this stage, in the quartzcrystal wafer 10W, the piezoelectric substrates 10 each including thevibrating section 12 and the thick section 13 come into continuouscontact with one another by a supporting narrow piece to be in a stateof being regularly arranged in a grid shape.

Furthermore, the external shape of the cross-section orthogonal to the Xaxis has been shown, but the external shape of the cross-sectionorthogonal to the Z′ axis will also be formed as shown in FIGS. 1A to 1Fby performing etching for both surfaces.

After Step S10 is completed, the thickness of the vibrating section 12of the piezoelectric substrate 10 regularly arranged in a grid shape onthe quartz crystal wafer 10W is measured using, for example, an opticaltechnique. When the measured thickness of the vibrating section 12 isthicker than a predetermined thickness, fine adjustment is performed forthe thickness so as to be included in the range of the predeterminedthickness.

Next, the procedure of manufacturing a piezoelectric vibrating elementin which the excitation electrodes 25 a and 25 b and the lead electrodes27 a and 27 b are formed in the piezoelectric substrate 10 after thethickness of the vibrating section 12 of the piezoelectric substrate 10formed on the quartz crystal wafer 10W is adjusted so as to be includedin the range of the predetermined thickness will be described using themanufacturing process diagram of the excitation electrodes and the leadelectrodes of the piezoelectric vibrating element shown in FIG. 11.

In Step S11, metal films M are formed over the entire front and rearsurfaces of the quartz crystal wafer 10W by forming a chrome (Cr) thinfilm by performing sputtering, or the like and laminating a gold (Au)thin film thereon.

Next in Step S12, resist are coated on the metal films M respectively soas so form resist films R.

In Step S13, using a mask pattern Mk for the lead electrodes 27 a and 27b and the pad electrodes 29 a and 29 b, the resist films R at thepositions corresponding to the lead electrodes 27 a and 27 b and the padelectrodes 29 a and 29 b on the front and rear surfaces are exposed tolight.

Next in Step S14, the resist films R are developed and then unnecessaryresist films R are peeled. Through the peeling, the exposed metal filmsM are melted by using a solution such as aqua regia, or the like so asto be removed. The resist films R at the positions corresponding to thelead electrodes 27 a and 27 b and the pad electrodes 29 a and 29 b areleft as they are.

Next in Step S15, metal films M are formed over the entire front andrear surfaces of the quartz crystal wafer 10W by forming a nickel (Ni)thin film by performing sputtering, or the like and laminating a gold(Au) thin film thereon. Further, resist films R are coated on the metalfilms M. In the drawing of Step S15, the metal film and the resist film(M+R) for the lead electrodes and the pad electrodes are expressed by areference symbol C in order to avoid complexity. Then, the resist filmsR at the position corresponding to the excitation electrodes 25 a and 25b are exposed to light using the mask pattern Mk for the excitationelectrodes 25 a and 25 b.

In Step S16, after the resist films R exposed to light are developed,unnecessary resist films R are peeled using a solution.

Next in Step S17, the metal films M exposed after the resist films R arepeeled are melted by a solution such as aqua regia and then removed. InStep S18, the reference symbol C (the metal film M and the resist film Rfor the lead electrodes and the pad electrodes) is restored to the metalfilm M and the resist film R.

In Step S19, after the unnecessary resist films R remaining on the metalfilms M are peeled, the excitation electrodes 25 a and 25 b of the metalfilm M (Ni+Au) and the lead electrodes 27 a and 27 b and the padelectrodes 29 a and 29 b not shown in the drawing of the metal film M(Cr+Au) are formed on the piezoelectric substrate 10.

After that, by breaking off the supporting narrow piece coming intocontinuous contact with the quartz crystal wafer 10W, a splitpiezoelectric vibrating element is obtained.

If wet-etching is performed for quartz crystal, however, the etchingprogresses along the Z axis, but etching anisotropy unique for quartzcrystal that an etching rate changes according to the direction of eachaxis of the quartz crystal is exhibited. Thus, the fact that adifference is shown on etched planes that appear due to the anisotropyof the etching according to a direction of each axis of quartz crystalhas been discussed hitherto in many academic papers and preceding patentliteratures that have set etch anisotropy as their research theme.However, despite such a background, there is no material that clearlyestablishes a system of the etch anisotropy of quartz crystal, so atpresent, there are various opinions according to the literature withregard to the presence of a phase difference in appearing crystal planessuch as whether the difference results from differences in generalconditions (the type of an etching solution, an etching rate, etchingtemperature, and the like) due to an extremely strong aspect of anano-processing technique.

Therefore, the inventors of the present application repeated etchingsimulations, trial manufacturing, and surface analysis and observationat a nano level for manufacturing a piezoelectric substrate usingphotolithography and wet-etching and then clarified that a piezoelectricvibrating element has the following aspects, and therefore, detailsthereof will be described below.

FIGS. 12A to 13E are diagrams showing schematic shapes of a recess 11 onthe AT cut quartz crystal wafer 10W formed by photolithography andwet-etching.

FIG. 12A is a plan view of the quartz crystal wafer 10W corresponding toStep S5 of FIG. 10. In this stage, the recess 11 is regularly formed onone surface of the quartz crystal wafer 10W in a grid shape. FIG. 12B isa cross-section in the X-axis direction in which each wall surface ofthe recess 11 shows an inclined surface, not a vertical surface. Thatis, a wall surface X1 in the −X-axis direction forms an inclined surfaceand a wall surface X2 in the +X-axis direction forms another inclinedsurface. If a groove orthogonal to the X axis is formed, a wall surfaceX3 of the groove in the ±X-axis direction is formed in a wedge shape.

FIGS. 12C to 12E are enlarged views of the wall surfaces X1 and X2 ofthe recess 11 and the wall surface X3 of the groove. The wall surface X1in the −X-axis direction is etched with inclination of about 62° withrespect to the X-Z′plane of the quartz crystal wafer 10W as shown inFIG. 12C. The wall surface X2 in the +X-axis direction is orthogonal)(90° to the X-Z′ plane of the quartz crystal wafer 10W and etchingprogresses, but after that, the etching further progresses to gradualinclination as shown in FIG. 12D. The bottom face of the formed recess11 is etched in parallel to the original plane (X-Z′ plane) of thequartz crystal wafer 10W. As a result, the vibrating section 12 turnsinto a plate shape of which the front and rear surfaces are parallel toeach other.

FIG. 12E is a cross-sectional view of the groove formed on the quartzcrystal wafer 10W. The cross-section of the groove formed orthogonal tothe X axis forms a wedge shape. Since the wall surface X3 of the grooveis formed with the wall surface X1 in the −X-axis direction and the wallsurface X2 in the +X-axis direction, the wedge shape is shown.

When an electrode is provided on the surface where the recess 11 isformed, it is necessary to be cautious about the wall surface orthogonalto the wall surface X2 formed in the +X-axis direction. It is desirableto avoid the wall surface because cracks tend to be generated in anelectrode film.

FIGS. 13A to 13E are diagrams showing wall surfaces of the recess 11formed on the quartz crystal wafer 10W, particularly wall surfaces ofthe cross-section thereof in the Z′-axis direction.

FIG. 13A is a plan view of the quartz crystal wafer 10W. FIGS. 13B to13E are cross-sectional views of the Z′-axis direction of the quartzcrystal wafer 10W taken from the +X-axis direction.

As shown in FIG. 13B, a wall surface Z1 in the +Z′-axis direction formsan inclined surface, and a wall surface Z2 in the −Z′-axis directionforms another inclined surface. If a groove orthogonal to the Z′ axis isformed, a wall surface Z3 of a cross-section of the groove shows a wedgeshape.

FIGS. 13C to 13E are enlarged view of the wall surfaces Z1 and Z2 of therecess 11 and the wall surface Z3 of the groove. As shown in FIG. 13C,the wall surface Z1 in the +Z′-axis direction is etched with relativelygradual inclination to the plane of the quartz crystal wafer 10W.

As shown in FIG. 13D, the wall surface Z2 in the −Z′-axis direction isetched with steep inclined surface Z2 a to the plane of the quartzcrystal wafer 10W, but successively, etching progresses with a graduallyinclined surface Z2 b and then a more gradually inclined surface Z2 c isformed.

FIG. 13E is a cross-sectional view of the groove formed orthogonal tothe Z′-axis direction showing the wall surface Z3 of a wedge-likecross-section. Since the wall surface Z3 of the groove is formed withthe wall surface Z1 in the +Z′-axis direction, a wall surface Z2 a inthe −Z′-axis direction, and an inclined surface Z2 b, substantially awedge-like cross-section is shown.

One of the characteristics of the embodiment is that miniaturization ofthe piezoelectric substrate 10 has been attempted by removing thegradually inclined surface Z2 c closer to the −Z′ axis than to thedashed line Zc and the thick section 17 formed continuous thereto asshown in FIG. 13D and the wall surface X1 closer to the −X axis than tothe dashed line Zc and the thick section 16 formed continuous thereto asshown in FIG. 12C through etching. As a result, the vibrating section 12is a part of the piezoelectric substrate 10 in which two adjacent sidesthereof are held by the L-shaped thick section 13.

Furthermore, the manufacturing method has been established on thepremise that the gradually inclined surface Z2 c and the thick section17 and the wall surface X1 and the thick section 16 are removedtogether. Thus, it has been realized that a larger area of a flatultra-thin portion that will serve as the vibrating section 12 issecured than in the configuration exemplified as a preceding techniquein which thick sections present in both ends of a vibration area areprovided along the X axis as in the related art.

As a result, it was possible to design the element sufficientlyconsidering that, in a thickness shear vibration mode in whichexcitation occurs in the vibration area, vibration displacementdistribution caused by anisotropy of an elastic constant shows anelliptical shape having a long diameter in the X-axis direction, and theratio of the long axis to the short axis is desirably 1.26:1, and thus,it was possible to design the element within the range of 1.14 to 1.39:1after considering unevenness in dimensions occurring in manufacturing,or the like.

FIGS. 14A and 14B are diagrams of the piezoelectric vibrating element 1shown in FIGS. 1A to 1F in more detail, FIG. 14A is a perspective viewthereof, and FIG. 14B shows a cut face of cross-section Q-Q in FIG. 1A.As shown in FIGS. 14A and 14B, in the external shape of thepiezoelectric vibrating element 1, an inclined surface appears on anedge face crossing the X axis. In other words, an inclined surface A1 ofFIG. 14A appears on an edge face on the −X-axis side and an inclinedsurface A2 of FIG. 14B appears on an edge face on the +X-axis side. Thecross-sectional shapes of the inclined surfaces A1 and A2 parallel tothe X-Y′ plane are different from each other.

In addition, for both of the inclined surfaces A1 and A2, a verticalwall surface as the wall surface X2 formed in the +X-axis direction asshown in FIGS. 12B and 12D does not appear in the vicinity where theedge faces and the front surface of the piezoelectric substrate 10. Thereason is that, in comparison to a necessary etching time for formingthe recess 11, the formation time of the inclined surfaces A1 and A2 hasa sufficient etching time since etching starts from the front and rearsurfaces of the piezoelectric substrate (quartz crystal substrate) 10and continues until the substrate is penetrated, and due to suchover-etching, a vertical wall surface does not appear.

It has been clarified that inclined faces a1 and a2 constituting theinclined surface A1 are substantially symmetric with respect to the Xaxis, and with regard to inclined faces b1, b2, b3, and b4 constitutingthe inclined surface A2, the inclined faces b1 and b4 and the inclinedfaces b2 and b3 are substantially symmetric with respect to the X axis.Furthermore, an inclination angle α of the inclined faces a1 and a2 withrespect to the X axis and an inclination angle β of the inclined facesb1 and b4 with respect to the X axis are in the relationship of β<α.

As shown in the first to third embodiments, as the piezoelectricvibrating elements 1, 2 and 3 of a high frequency using the fundamentalmode is miniaturized and mass-produced, and the slit 20 is providedbetween the thick section 13 and the vibrating section 12, expansion ofstress caused by adhesion and fixation can be suppressed, and therefore,there is an effect of obtaining the piezoelectric vibrating elements 1,2 and 3 that are excellent in the frequency-temperature characteristic,a CI-temperature characteristic, and the frequency aging characteristic.

In addition, as shown in FIGS. 3A and 3B, since the excitationelectrodes 25 a and 25 b, the lead electrodes 27 a and 27 b, and the padelectrodes 29 a and 29 b respectively uses metal materials withdifferent compositions and are configured to have optimum thicknesses,there is an effect of obtaining a piezoelectric vibrating element havinga small CI value of the main vibration, and a high ratio of a CI valueof proximate spurious vibrations to the CI value of the main vibration,that is, a high CI value ratio.

In addition, as shown in FIGS. 1A to 1F and FIGS. 3A and 3B, since theexcitation electrodes 25 a and 25 b are formed of a laminated film ofnickel and gold and the lead electrodes 27 a and 27 b and the padelectrodes 29 a and 29 b are formed of a laminated film of chrome andgold, there is an effect of obtaining a piezoelectric vibrating elementthat sufficiently tolerates bonding while having a small CI value of themain vibration, and a high ratio of a CI value of proximate spuriousvibrations to the CI value of the main vibration, that is a high CIvalue ratio.

Since the piezoelectric substrate 10 is formed as shown in the cuttingangle diagram of FIG. 2, there is an effect that the piezoelectricvibrating element with required specifications can be configured in amore proper cutting angle, and a high-frequency piezoelectric vibratingelement having the frequency-temperature characteristic conforming withthe specifications, a low CI value, and a high CI value ratio isobtained.

In addition, since performance and experience of photolithography andetching can be utilized when an AT cut quartz crystal substrate is usedfor the piezoelectric substrate 10, there is an effect not only thatmass production of piezoelectric substrates is possible with highprecision, but also that mass production of piezoelectric vibratingelements having a low CI value and a high CI value ratio is possible.

FIGS. 15A and 15B are diagrams showing a configuration of apiezoelectric resonator 5 according to an embodiment of the invention,FIG. 15A is a plan view in which a cover member is omitted, and FIG. 15Bis a vertical cross-sectional view.

As shown in FIGS. 15A and 15B, the piezoelectric resonator 5 includes,for example, the piezoelectric vibrating element 1 and a packageaccommodating the piezoelectric vibrating element 1. The package isconstituted by a package main body 40 formed in a rectangular box shape,and a cover member 49 formed of metal, ceramic, glass, or the like.Furthermore, in description below, the direction in which the covermember 49 is placed over the package main body 40 in FIG. 15B will beregarded as the upper direction (upper surface side) for the sake ofconvenience.

The package main body 40 is formed by laminating a first substrate 41, asecond substrate 42, and a third substrate 43 in such a way that aceramic green sheet of aluminum oxide as an insulating material ismolded in a box shape and then sintered. A plurality of mountingterminals 45 are formed on the external bottom surface of the firstsubstrate 41. The third substrate 43 is a circular body without thecenter portion, and a metal seal ring 44 of, for example, kovar, or thelike is formed on the upper circumferential edge of the third substrate43.

With the third substrate 43 and the second substrate 42, a recessedportion (cavity) for accommodating the piezoelectric vibrating element 1is formed. At a predetermined position on the upper surface of thesecond substrate 42, an element-mounting pad 47 that is electricallyconnected to the mounting terminal 45 with a conductor 46 is provided.The position of the element-mounting pad 47 is determined so as tocorrespond to that of the pad electrode 29 a formed in the first thicksection main body 14 a when the piezoelectric vibrating element 1 isplaced.

When the piezoelectric vibrating element 1 is to be fixed, first, aconductive adhesive 30 is applied onto the pad electrode 29 a of thepiezoelectric vibrating element 1, the upper and lower sides of thepiezoelectric vibrating element 1 are reversed (turned over) so as to beplaced on the element-mounting pad 47 of the package main body 40, andthen weight is exerted thereon. As a characteristic of the conductiveadhesive 30, the magnitude of stress (∝ strain) caused by the conductiveadhesive 30 becomes great in order of a silicon-based adhesive, anepoxy-based adhesive, and a polyimide-based adhesive. In addition, theamount of degassing becomes great in order of a polyimide-basedadhesive, an epoxy-based adhesive, and a silicon-based adhesive. Inconsideration of a temporal change, a polyimide-based adhesive with asmall amount of degassing was used as the conductive adhesive 30.

In order to harden the conductive adhesive 30 of the piezoelectricvibrating element 1 mounted on the package main body 40, the package isfed into a high-temperature furnace of a predetermined temperature for apredetermined time. After the conductive adhesive 30 is hardened, thepad electrode 29 b shown on the front surface side after being reversedand an electrode terminal 48 of the package main body 40 areelectrically connected by a bonding wire BW. As shown in FIG. 15B, sincethe portion at which the piezoelectric vibrating element 1 is supportedby and fixed to the package main body 40 is one spot (one point), thatis, only the portion to which the pad electrode 29 a and theelement-mounting pad 47 are fixed, the magnitude of stress resultingfrom support and fixation can be reduced.

After performing an annealing process, a frequency is adjusted byincreasing or decreasing the mass of the excitation electrodes 25 a and25 b. The cover member 49 is placed on the seal ring 44 formed on theupper surface of the package main body 40, and then the cover member 49is sealed by performing seam welding in vacuum or in the atmosphere ofnitrogen (N₂) gas, whereby the piezoelectric resonator 5 is completed.Alternatively, there is a method in which the cover member 49 is placedon low-melting-point glass coated over the upper surface of the packagemain body 40 and then melted so as to come into tight contact with thepackage. Also in this case, the piezoelectric resonator 5 is completedin such a way that the inside of the cavity of the package is madevacuum or filled with inert gas such as nitrogen (N₂) gas. Furthermore,vacuum described in the present specification refers to low-pressureatmosphere or a low-vacuum state.

In the respective piezoelectric vibrating elements 1, 2, and 3 shown inFIGS. 1A to 1F, FIGS. 6A to 6C, and FIGS. 7A to 7C, the pad electrodes29 a and 29 b disposed so as to respectively face the front and rearsurface of the piezoelectric substrate 10 are formed. As shown in FIGS.15A and 15B, when the package main body 40 accommodates thepiezoelectric vibrating element 1, the piezoelectric vibrating element 1is turned over, and the pad electrode 29 a and the element-mounting pad47 of the package main body 40 are fixed and connected to each otherwith the conductive adhesive 30. The pad electrode 29 b shown on thefront surface side after being reversed and the electrode terminal 48 ofthe package main body 40 are connected by the bonding wire BW. In thismanner, if a portion for supporting the piezoelectric vibrating element1 is one point, stress caused by the conductive adhesive 30 becomessmall. In addition, if the piezoelectric vibrating element 1 is turnedover so as to arrange the bigger excitation electrode 25 b in the uppersurface when being accommodated in the package main body 40, frequencyadjustment of the piezoelectric vibrating element 1 becomes easy.

In addition, the piezoelectric resonator 5 may be configured by using apiezoelectric vibrating element in which the interval of the padelectrodes 29 a and 29 b is set apart. Also in this case, apiezoelectric resonator can be configured in the same manner of thepiezoelectric resonator 5 described in FIGS. 15A and 15B.

Furthermore, as shown in FIG. 9, the piezoelectric resonator 5 may beconfigured by using the piezoelectric vibrating element 1″ in which theinterval of the pad electrodes 29 a and 29 b is set apart on the sameplane. In this case, the piezoelectric vibrating element 1″ isconfigured so as to be supported and fixed in such a way that theconductive adhesive 30 is applied onto the respective pad electrodes 29a and 29 b, reversed, placed on the element-mounting pad 47 formed inthe package main body 40, and then weight is exerted thereon. Theconfiguration is appropriate for reducing the height, but since thesupported portions are two points, which are the pad electrodes 29 a and29 b, there is concern that stress caused by the conductive adhesive 30slightly increases.

In the embodiment of the piezoelectric resonator 5 above, an example inwhich a laminated plate is used over the package main body 40, however,a piezoelectric resonator may be configured by using a single-layeredceramic plate for the package main body 40 and a cap obtained byperforming a drawing process for a cover.

Since the piezoelectric resonator shown in FIGS. 15A and 15B isconfigured using the piezoelectric vibrating elements 1, 2, and 3 shownin FIGS. 1A to 1F, FIGS. 6A to 6C, and FIGS. 7A to 7C, a high-frequencypiezoelectric resonator is miniaturized, a portion supporting thepiezoelectric vibrating elements 1, 2, and 3 is one point, and stresscaused by the conductive adhesive 30 can be reduced by providing theslit 20 between the thick section 13 and the vibrating section 12, andtherefore, there is an effect of obtaining a piezoelectric resonatorexcellent in frequency reproducibility, the frequency temperaturecharacteristic, the CI-temperature characteristic, and the frequencyaging characteristic.

In addition, as shown in the embodiment of FIGS. 3A and 3B, since theelectrode material of the excitation electrodes 25 a and 25 b and theelectrode material of the lead electrodes 27 a and 27 b and the padelectrodes 29 a and 29 b differ from each other, and the piezoelectricvibrating elements 1, 2, and 3 of which film thicknesses are configuredto be optimum for respective functions are used, there is an effect ofobtaining the piezoelectric vibrating elements 1, 2, and 3 having asmall CI value of the main vibration, and a high ratio of a CI value ofproximate spurious vibrations to the CI value of the main vibration,that is, a high CI value ratio.

FIG. 16 is a vertical cross-sectional view showing an embodiment of anelectronic device according to the invention. The electronic device 6generally includes the piezoelectric vibrating element 1 (which may bethe piezoelectric vibrating elements 2 or 3), a thermistor Th that is atemperature-sensing element as a temperature sensor of one electroniccomponent, and a package accommodating the piezoelectric vibratingelement 1 and the thermistor Th. Also in description below, thedirection in which the cover member 49 is placed over the package mainbody 40 will be regarded as the upper direction (upper surface side) andthe opposite direction to the upper direction as the lower direction(lower surface side).

The package includes a package main body 40 a and the cover member 49.The package main body 40 a has a cavity 31 formed on the upper surfaceside for accommodating the piezoelectric vibrating element 1, and arecess 32 formed outside on the lower surface side for accommodating thethermistor Th. In an edge of the inner bottom surface of the cavity 31,the element-mounting pad 47 is provided, and the element-mounting pad 47is electrically connected to the mounting terminal 45 with the conductor46. The conductive adhesive 30 is applied onto the pad electrode 29 a ofthe piezoelectric vibrating element 1, and then the element is reversed,and placed on the element-mounting pad 47. The pad electrode 29 b shownon the front surface side after being reversed and the electrodeterminal 48 are connected by the bonding wire BW.

The seal ring 44 composed of kovar, or the like is burned on the upperportion of the package main body 40 a, the cover member 49 is placedover the seal ring 44 and welded using a resistance welder so as toair-tightly seal the cavity 31. The inside of the cavity 31 may be madevacuum, or filled with inert gas. A terminal of the thermistor Th isconnected to the recess 32 on the rear surface using solder balls, orthe like, whereby the electronic device 6 is completed.

In the above embodiment, an example has been described in which therecess 32 is formed outside on the lower surface side of the packagemain body 40 a to mount an electronic component, however, the recess 32may be formed on the inner bottom surface of the package main body 40 ato mount the electronic component.

In addition an example has been described in which the package main body40 a accommodates the piezoelectric vibrating element 1 and thethermistor Th, however, it is desirable to configure an electronicdevice by accommodating at least one of a thermistor, a capacitor, areactance element, and a semiconductor element as an electroniccomponent that the package main body 40 a accommodates.

If the electronic device 6 is configured in which the package main body40 a accommodates the piezoelectric vibrating element 1 and thethermistor Th as in the embodiment shown in FIG. 16, the thermistor Thof the temperature-sensing element is disposed at an excessively closeposition to the piezoelectric vibrating element 1, and therefore, thereis an effect of swiftly sensing a temperature change of thepiezoelectric vibrating element 1.

In addition, since a small-sized high-frequency electronic device can beconfigured by constituting the electronic device with the piezoelectricvibrating element according to the embodiment of the invention and theabove-described electronic component, there is an effect of using thedevice in various applications.

Furthermore, if an electronic device (piezoelectric device) isconfigured using any one of a variable capacitance element, athermistor, an inductor, and a capacitor as an electronic component,there is an effect of realizing a small-sized electronic device moresuitable for required specifications at low cost.

FIGS. 17A and 17B are diagrams showing a configuration of apiezoelectric oscillator 7 that is one kind of an electronic deviceaccording to an embodiment of the invention, FIG. 17A is a plan view inwhich a cover member is omitted, and FIG. 17B is a verticalcross-sectional view. The piezoelectric oscillator 7 includes a packagemain body 40 b, the cover member 49, the piezoelectric vibrating element1, an IC component 51 mounted with an oscillator circuit for excitingthe piezoelectric vibrating element 1, and an electronic component 52such as a variable capacitance element for changing capacitance byvoltage, a thermistor for changing resistance by temperature, aninductor, or the like.

The (polyimide-based) conductive adhesive 30 is applied onto the padelectrode 29 a of the piezoelectric vibrating element 1, the element isreversed so as to be placed on an element-mounting pad 47 a of thepackage main body 40 b, and the pad electrode 29 a and theelement-mounting pad 47 a are electrically connected to each other. Thepad electrode 29 b shown on the front surface side after being reversedand the electrode terminal 48 of the package main body 40 b areconnected by the bonding wire BW.

The IC component 51 is fixed to a predetermined position of the packagemain body 40 b, and terminals of the IC component 51 is connected toelectrode terminals 55 of the package main body 40 b by the bonding wireBW so as to achieve electric conduction. In addition, the electroniccomponent 52 is placed at a predetermined position of the package mainbody 40 b and connected using a metal bump.

The package main body 40 b is made vacuum or filled with inert gas suchas nitrogen gas, and sealed by the cover member 49, whereby thepiezoelectric oscillator (electronic device) 7 is completed.

In the technique of connecting the pad electrode 29 b and the electrodeterminal 48 of the package main body 40 b with the bonding wire BW, theportion supporting the piezoelectric vibrating element 1 is one pointand stress caused by the conductive adhesive 30 becomes small. Inaddition, since the bigger excitation electrode 25 b is disposed on theupper surface after the upper and lower sides of the piezoelectricvibrating element 1 is reversed during accommodation of the package mainbody 40 b, frequency adjustment of the piezoelectric oscillator(electronic device) 7 becomes easy.

In the piezoelectric oscillator (electronic device) 7 shown in FIGS. 17Aand 17B, the piezoelectric vibrating element 1, the IC component 51, andthe electronic component 52 are disposed on the same package main body40 b, however, in the piezoelectric oscillator 7′ that is a modificationexample of the piezoelectric oscillator 7 shown in FIG. 18, the cavity31 formed on the upper side accommodates the piezoelectric vibratingelement 1 using an H-shaped package main body 60, the inside of thecavity 31 is made vacuum or filled with nitrogen (N₂) gas, and sealed bya cover member 61. The IC component 51 on which an amplifier circuit, anoscillator circuit for exciting the piezoelectric vibrating element 1,or the like is mounted and the electronic component 52 such as avariable capacitance element or an inductor, a thermistor, a capacitor,or the like depending on necessity in the lower portion are connected toterminals 67 of the package main body 60 via a metal bump (Au bump) 68.

Since, in the piezoelectric oscillator 7′ that is a modification exampleof the electronic device according to an embodiment of the invention,the piezoelectric vibrating element 1, the IC component 51, and theelectronic component 52 are separated, and the piezoelectric vibratingelement 1 is solely air-tightly sealed, the frequency agingcharacteristic of the piezoelectric oscillator 7′ is excellent.

By configuring the electronic device (for example, a voltage-controlledtype piezoelectric oscillator) as shown in FIGS. 17A to 18, there is aneffect of obtaining a small-sized voltage-controlled piezoelectricoscillator of a high frequency (for example, the 490 MHz band) havingthe excellent frequency reproducibility, frequency-temperaturecharacteristic, and frequency aging characteristic. In addition, since apiezoelectric device uses the piezoelectric vibrating element 1 of thefundamental mode, a capacitance ratio is low and a frequency variablewidth expands. Furthermore, there is an effect of obtaining avoltage-controlled piezoelectric oscillator with a satisfactory S/Nratio.

In addition, there is another effect that a piezoelectric oscillator, atemperature-compensated piezoelectric oscillator, or the like can beconfigured as a piezoelectric device, and a piezoelectric oscillatorhaving the excellent frequency reproducibility, frequency agingcharacteristic, and frequency-temperature characteristic can beconfigured.

Electronic Apparatus

Next, an electronic apparatus to which the piezoelectric resonator 5using the piezoelectric vibrating element 1 according to an embodimentof the invention will be described in detail based on FIGS. 19 to 23.

FIG. 19 is a schematic configuration diagram showing a configuration ofan electronic apparatus according to the embodiment. The electronicapparatus 8 includes the above-described piezoelectric resonator 5. Asthe electronic apparatus 8 using the piezoelectric resonators, atransmission apparatus, or the like can be exemplified. Thepiezoelectric resonator 5 in the electronic apparatus 8 is used as areference signal source, a voltage-controlled piezoelectric oscillator(VCXO), or the like and can provide a small-sized electronic apparatuswith satisfactory features.

By using the piezoelectric resonator 5 of the present embodiment in theelectronic apparatus 8 as shown in the pattern diagram of FIG. 19, thereis an effect of configuring an electronic apparatus having excellentfrequency stability at a high frequency and a reference frequency sourcewith a satisfactory S/N ratio.

FIG. 20 is a perspective view showing a schematic configuration of aportable type (or note type) personal computer as an electronicapparatus including the piezoelectric resonator 5 according to anembodiment of the invention. In the diagram, the personal computer 1100is constituted by a main body section 1104 including a keyboard 1102 anda display unit 1106 including a display section 100, and the displayunit 1106 is supported rotatable with respect to the main body section1104 via a hinge structure section. In such a personal computer 1100,the piezoelectric resonator 5 is built.

FIG. 21 is a perspective view showing a schematic configuration of amobile telephone (also including a PHS) as an electronic apparatusincluding the piezoelectric resonator 5 according to an embodiment ofthe invention. In the drawing, the mobile telephone 1200 include aplurality of operation buttons 1202, an earpiece 1204, and a mouthpiece1206, and a display section 100 is disposed between the operationbuttons 1202 and the earpiece 1204. In such a mobile telephone 1200, thepiezoelectric resonator 5 is built.

FIG. 22 is a perspective view showing a schematic configuration of adigital still camera as an electronic apparatus including thepiezoelectric resonator 5 according to an embodiment of the invention.In addition, the drawing shows connection to an external device in asimple manner. Herein, in a general camera, a silver halide photographicfilm is exposed to light from an optical image of a subject, however, inthe digital still camera 1300, an optical image of a subject undergoesphotoelectric conversion by an imaging device such as a CCD (ChargeCoupled Device) so as to generate an imaging signal (image signal).

On the back surface of a case (body) 1302 of the digital still camera1300, the display section 100 is provided, display is performed based onan imaging signal of the CCD, and thus, the display section 100functions as a finder that allows the subject to be displayed as anelectronic image. In addition, on the front surface side (rear surfaceside in the drawing) of the case 1302, a light reception unit 1304 thatincludes an optical lens (imaging optical system), the CCD, and the likeis provided.

When a photographer perceives an image of a subject displayed on thedisplay section 100 and then presses a shutter button 1306, an imagingsignal of the CCD at the time point is transferred to and then stored ina memory 1308. In addition, in the digital still camera 1300, a videosignal output terminal 1312 and a data communication input and outputterminal 1314 are provided on aside surface of the case 1302.Furthermore, as shown in the drawing, a television monitor 1430 isconnected to the video signal output terminal 1312 and a personalcomputer 1440 is connected to the data communication input and outputterminal 1314 respectively if necessary. Moreover, with a predeterminedoperation, the imaging signal stored in the memory 1308 is configured tobe output to the television monitor 1430 and the personal computer 1440.In such a digital still camera 1300, the piezoelectric resonator 5 isbuilt.

Furthermore, the piezoelectric resonator 5 according to an embodiment ofthe invention can be applied to other electronic apparatuses, forexample, ink jet discharge devices (for example, ink jet printers),lap-top personal computers, televisions, video cameras, video taperecorders, car navigation devices, pagers, electronic organizers(including those with a communication function), electronicdictionaries, electronic calculators, electronic game devices, wordprocessors, workstations, videophones, security television monitors,electronic binoculars, POS terminals, medical devices (for example,electronic thermometers, sphygmomanometers, blood glucose meters,electrocardiogram measuring devices, ultrasonographs, and electronicendoscopes), fishfinders, various measuring devices, meters and gauges(for example, meters and gauges of automobiles, aircraft, and vessels),flight simulators, and the like, in addition to the personal computer(portable type personal computer) of FIG. 20, the mobile telephone ofFIG. 21, and the digital still camera of FIG. 22.

Mobile Object

FIG. 23 is a perspective view schematically showing a vehicle as anexample of a mobile object. In the vehicle 106, the piezoelectricresonator 5 according to an embodiment of the invention is mounted. Asshown in the drawing, for example, the vehicle 106 as a mobile objectincludes the piezoelectric resonator 5 using a gyro element 2 and anelectronic control unit 108 for controlling a tier 109, and the like ismounted on a vehicle body 107. In addition, the piezoelectric resonator5 can be broadly applied to electronic control units (ECUs) including akeyless entry system, an immobilizer, a car navigation system, a carair-conditioner, an anti-lock braking system (ABS), an air bag, a tirepressure monitoring system (TPMS), an engine controller, a batterymonitor of a hybrid or electronic vehicle, a vehicle body posturecontrol system, and the like.

First Modification Example

As a technique of further reducing and suppressing stress caused byinstallation of a piezoelectric vibrating element, a configuration asshown below can be employed.

The piezoelectric substrate 10 in a modification example of FIG. 24Aincludes the thin vibrating section 12 having a vibration area and thethick section 13 that is provided on a circumferential edge of thevibrating section 12 and thicker than the vibrating section 12. Thethick section 13 includes the first thick section main body 14 a and thesecond thick section main body 15 a, and on the inner walls of the firstand the second thick section main bodies 14 a and 15 a on the vibratingsection 12 side, the first and the second inclined sections 14 b and 15b are provided. In the first thick section main body 14 a, the firstinclined section 14 b and a mounting portion F are arranged in anextended manner, interposing a buffer section S provided in thedirection of a margin of the first thick section main body. The buffersection S has the slit 20 between the mounting section F and the firstinclined section 14 b. The mounting section F has chamfered sections 21at both edge portions in the direction orthogonal to the direction inwhich the buffer section S and the thick section 13 are arranged.

The piezoelectric substrate 10 of FIG. 24B includes the thin vibratingsection 12 having a vibration area and the thick section 13 that isprovided at a circumferential edge of the vibrating section 12 and isthicker than the vibrating section 12. The thick section 13 includes thefirst thick section main body 14 a and the second thick section mainbody 15 a, and on the inner walls of the first and the second thicksection main bodies 14 a and 15 a on the vibrating section 12 side, thefirst and the second inclined sections 14 b and 15 b are provided. Inthe first thick section main body 14 a, the first inclined section 14 band the mounting portion F are arranged in an extended manner,interposing the buffer section S provided in the direction of a marginof the first thick section main body. The buffer section S has the slit20 between the mounting section F and the first inclined section 14 b.

The mounting section F has cutout portions 22 at both ends thereof inthe direction orthogonal (hereinafter, referred to as an orthogonaldirection) to the direction in which the buffer section S and the thicksection 13 are arranged. The longitudinal direction (stretchingdirection) of the slit 20 is parallel to the orthogonal direction. Inaddition, the width of the mounting section F in the orthogonaldirection is set to be narrower than the width of the slit in thelongitudinal direction. Both ends of the slit in the longitudinaldirection are provided closer to the outer circumference of the buffersection S in the orthogonal direction than the both ends of the mountingsection F.

The piezoelectric substrate 10 of FIG. 24C includes the thin vibratingsection 12 having a vibration area and the thick section 13 that isprovided at a circumferential edge of the vibrating section 12. Thethick section 13 includes the first thick section main body 14 a and thesecond thick section main body 15 a, and on the inner walls of the firstand the second thick section main bodies 14 a and 15 a on the vibratingsection 12 side, the first and the second inclined sections 14 b and 15b are provided. To the first thick section main body 14 a, the buffersection S and the mounting section F are continuously connected in thisorder. In addition, in the first thick section main body 14 a, shouldersare provided of which both ends in the direction orthogonal(hereinafter, referred to as an orthogonal direction) to the directionin which the buffer section S and the thick section 13 are arrangedfurther protrude than the total width of the second thick section mainbody 15 a and the vibrating section 12. The buffer section S has theslit 20 between the mounting section F and the first inclined section 14b. The mounting section F has the cutout portions 22 at both endsthereof in the orthogonal direction.

The configurations shown in FIGS. 25A to 25C are characterized oftwo-point support, different from the configurations shown in FIGS. 24Ato 24C, that is, a form of mounting sections F1 and F2 horizontallyprovided.

Furthermore, in FIGS. 24A to 25C, the first and the second inclinedsections 14 b and 15 b are shown on the inner walls of the first and thesecond thick section main bodies 14 a and 15 a of the thick section 13,and on the other hand, inclined surfaces as shown in FIGS. 14A and 14Bare not shown on the outer side wall surfaces of the thick section 13,however, such inclined sections and inclined surfaces may be formed atthe portions corresponding to those as shown in FIGS. 14A and 14B.

Furthermore, each reference numerals in FIGS. 24A to 25C corresponds tothe portions denoted by the same reference numerals of theabove-described embodiments.

Second Modification Example

Further, FIG. 26A is a plane view of a piezoelectric vibrating element1A, FIG. 26B shows an enlarged plan view of a pad electrode 29 a(mounting section F) of the piezoelectric vibrating element 1A, and FIG.26C shows a cross-sectional view of the pad electrode 29 a (mountingsection F). In the pad electrode 29 a (mounting section F), an adhesivearea is extended by forming the surface in an uneven shape so as toimprove adhesion strength.

The entire disclosure of Japanese Patent Application No. 2011-179405,filed Aug. 19, 2011 and Japanese Patent Application No. 2012-143908,filed Jun. 27, 2012 is expressly incorporated by reference herein.

What is claimed is:
 1. A resonator having a resonating element, theresonator comprising: a substrate that includes a vibrating sectionhaving a vibration area and a thick section that is formed integrallywith the vibrating section, a thickness of the thick section beinglarger than a thickness of the vibrating section; and an excitationelectrode that is provided in the vibration area, wherein the thicksection includes a first thick section that is provided along one sideof the vibrating section, a first plane of the first thick sectionprotrudes further than a second plane of the vibrating section, thefirst thick section includes a first inclined section of which athickness increases as the first thick section is apart from onecircumferential edge thereof that comes into continuous contact with theone side of the vibrating section toward the other circumferential edge,and a first thick section main body that comes into continuous contactwith the other circumferential edge of the first inclined section, apackage houses the resonating element, and at least one slit is providedin the first thick section, the at least one slit extends along the oneside of the vibrating section, the at least one slit has a vacant insidespace, the at least one slit is formed from a to surface of the firstthick section to a bottom surface of the first thick section so that theslit penetrates the first thick section, and the at least one slit isprovided between the vibrating section and a region where the thicksection is supported by the package.
 2. The resonator according to claim1, wherein centering around an X axis of an orthogonal coordinate systemincluding the X axis as an electrical axis, a Y axis as a mechanicalaxis, and a Z axis as an optical axis that are crystal axes of quartzcrystal, the substrate sets an axis obtained by inclining the Z axistoward the −Y direction of the Y axis to a Z′ axis, sets an axisobtained by inclining the Y axis toward the +Z direction of the Z axisto a Y′ axis, has a plane including the X axis and the Z′ axis as a mainplane, and is a quartz crystal substrate having thickness in thedirection along the Y′ axis.
 3. The resonator according to claim 2,wherein the first plane of the first thick section protrudes from thesecond plane of the vibrating section in the +Y direction of the Y′axis.
 4. The resonator according to claim 2, wherein the first thicksection is provided in the +X direction of the X axis.
 5. The resonatoraccording to claim 1, wherein the slit is provided in the first thicksection main body along a boundary between the first inclined sectionand the first thick section main body.
 6. The resonator according toclaim 1, wherein the slit is provided within the first inclined sectionas being spaced apart from the one side of the vibrating section.
 7. Theresonator according to claim 1, wherein the slit includes a first slitthat is provided in the first thick section main body, and a second slitthat is provided within the first inclined section as being spaced apartfrom the one side of the vibrating section.
 8. The resonator accordingto claim 7, wherein the first slit is provided in the first thicksection main body along a boundary between the first inclined sectionand the first thick section main body.
 9. An electronic devicecomprising: the resonator according to claim 1; an electronic component;and the package in which the resonating element and the electroniccomponent are accommodated.
 10. The electronic device according to claim9, wherein the electronic component is any one of a variable capacitanceelement, a thermistor, an inductor, and a capacitor.
 11. An electronicdevice comprising: the resonator according to claim 1; an oscillatorcircuit that drives the resonating element; and the package in which theresonating element and the oscillator circuit are accommodated.
 12. Anelectronic apparatus comprising: the resonator according to claim
 1. 13.A mobile object comprising: the resonator according to claim
 1. 14. Theresonator according to claim 1, wherein one surface of the substrate iseven, and the other surface of the substrate is uneven.
 15. Theresonator according to claim 1, wherein the thick section furtherincludes a second thick section that is provided along another side ofthe vibrating section, the another side is located next to the one sideof the vibrating section, the first thick section is continuous to thesecond thick section by each one end thereof, and a third plane of thesecond thick section protrudes further than the second plane of thevibrating section.
 16. The resonator according to claim 15, whereincentering around an X axis of an orthogonal coordinate system includingthe X axis as an electrical axis, a Y axis as a mechanical axis, and a Zaxis as an optical axis that are crystal axes of quartz crystal, thesubstrate sets an axis obtained by inclining the Z axis toward the −Ydirection of the Y axis to a Z′ axis, sets an axis obtained by incliningthe Y axis toward the +Z direction of the Z axis to a Y′ axis, has aplane including the X axis and the Z′ axis as a main plane, is a quartzcrystal substrate having thickness in the direction along the Y′ axis,and a second thick section is provided along another side of thevibrating section, the another side is located next to the one side ofthe vibrating section, and the second thick section is provided in the+Z′ direction of the Z′ axis.
 17. A resonator having a resonatingelement, the resonator comprising: a substrate that is formed in aquadrangle shape, the substrate that has first and second surfaceopposite to each other, the second surface being even; a vibrator thatis formed on the first surface of the substrate along first and secondsides of the substrate; a first thick member that is formed on the firstsurface of the substrate along a third side of the substrate, the firstthick member being continuously connected to the vibrator; a secondthick member that is formed on the first surface of the substrate alonga fourth side of the substrate, the second thick member beingcontinuously connected to the vibrator and the first thick member; andan excitation electrode that is provided at the vibrator, wherein afirst top surface of the first thick member and a second top surface ofthe second thick member are protruded from a third top surface of thevibrator, the first thick member has a slope that is continuously formedfrom an edge of the first top surface of the first thick member towardan edge of the third top surface of the vibrator, and the first thickmember has a slit that has a vacant inside space, the slit extends alongthe third side of the substrate, and the slit is formed from the firstto surface of the first thick member to the second surface of thesubstrate so that the slit penetrates the first thick member, a packagehouses the resonating element, and the slit is provided between thevibrator and a region where the first thick member is supported by thepackage.
 18. The resonator according to claim 17, wherein the slit isformed in the edge of the first top surface of the first thick member.19. The resonator according to claim 18, wherein the first thick memberhas another slit that has a vacant inside space, and the another slit isformed in the slope of the first thick member.
 20. The resonatoraccording to claim 17, wherein the slit is formed in the slope of thefirst thick member.